package com.learm.socket.nio;

import java.io.IOException;
import java.net.InetSocketAddress;
import java.nio.ByteBuffer;
import java.nio.channels.SelectionKey;
import java.nio.channels.Selector;
import java.nio.channels.ServerSocketChannel;
import java.nio.channels.SocketChannel;
import java.util.Date;
import java.util.Iterator;
import java.util.Set;

public class MultiplexerTimeServer implements Runnable {

    private Selector selector;

    private ServerSocketChannel serverChannel;

    private volatile boolean stop;

    public static void main(String[] args) {
        new Thread(new MultiplexerTimeServer(8080)).start();
    }

    /**
     * 初始化多路复用器，绑定监听端口
     * @param port
     */
    public MultiplexerTimeServer(int port) {
        try {
            selector = Selector.open();
            serverChannel = ServerSocketChannel.open();
            serverChannel.configureBlocking(false);
            serverChannel.socket().bind(new InetSocketAddress(port),1024);
            serverChannel.register(selector, SelectionKey.OP_ACCEPT);
            System.out.println("The time server is start in port：" + port);

        } catch (IOException e) {
            e.printStackTrace();
            System.exit(1);
        }
    }

    public void stop(){
        this.stop = true;
    }

    @Override
    public void run() {
        while (!stop){
            try {
                selector.select(10000);
                Set<SelectionKey> selectedKeys = selector.selectedKeys();
                Iterator<SelectionKey> it = selectedKeys.iterator();
                SelectionKey key = null;
                while (it.hasNext()){
                    key = it.next();
                    it.remove();
                    //todo
                    try {
                        handleInput(key);
                    } catch (IOException e) {
                        e.printStackTrace();
                        if(null != key){
                            key.cancel();
                            if(key.channel() != null){
                                key.channel().close();
                            }
                        }
                    }
                }

            } catch (Throwable e) {
                e.printStackTrace();
            }
        }
        // 多路复用器关闭后，所有注册在上面的 CHANNEL 和 Pipe 等资源都会被自动去注册并关闭，所以不需要重复释放资源
        if(selector != null){
            try {
                selector.close();
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
    }

    private void handleInput(SelectionKey key) throws IOException {
        if (key.isValid()){
            if (key.isAcceptable()){
                // 处理新接入的请求消息
                ServerSocketChannel ssc = (ServerSocketChannel) key.channel();
                SocketChannel sc = ssc.accept();
                sc.configureBlocking(false);
                sc.register(selector, SelectionKey.OP_READ);
            }else if(key.isReadable()){
                SocketChannel sc = (SocketChannel)key.channel();
                ByteBuffer readBuffer = ByteBuffer.allocate(1024);
                int readBytes = sc.read(readBuffer);
                if(readBytes>0){
                    readBuffer.flip();
                    byte[] bytes = new byte[readBuffer.remaining()];
                    readBuffer.get(bytes);
                    String body = new String(bytes, "UTF-8");
                    System.out.println("The time server receive order：" + body);

                    String currentTime = "Query Time Order".equalsIgnoreCase(body)?new Date(System.currentTimeMillis()).toString():"Bad Order";
                    // todo
                    doWrite(sc, currentTime);
                }
            }
        }
    }

    private void doWrite(SocketChannel channel, String response) throws IOException {

        if(response != null && response.trim().length()>0){
            byte[] bytes = response.getBytes();
            ByteBuffer writeBuffer = ByteBuffer.allocate(bytes.length);
            writeBuffer.put(bytes);
            writeBuffer.flip();
            channel.write(writeBuffer);

        }
    }
}
